197 
 WTPA45 PHFO 211504
 TCDCP5
 
 TROPICAL STORM MALIA DISCUSSION NUMBER  12
 NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   CP052015
 500 AM HST MON SEP 21 2015
 
 THE LOW LEVEL CENTER OF CIRCULATION /LLCC/ OF FIVE-C MOVED CLOSER
 TO THE DEEP CONVECTION EARLIER TONIGHT. ABOUT THE SAME TIME...GALE
 FORCE WINDS BECAME EVIDENT IN AN 0827Z SCATTEROMETER PASS. ONCE THIS
 BECAME EVIDENT...A SPECIAL ADVISORY WAS ISSUED AT 1200Z TO UPGRADE
 TROPICAL DEPRESSION FIVE-C TO TROPICAL STORM MALIA...PRONOUNCED
 MAH-LEE-AH. ADDITIONAL CONFIRMATION FOR THIS CHANGE IN STATUS OF
 THE SYSTEM WERE THE LATEST SUBJECTIVE DVORAK CURRENT INTENSITY
 ESTIMATES...2.5/35 KT FROM JTWC AND HFO...AND 2.0/30 KT FROM SAB.
 THE 1200Z UW-CIMSS ADT ESTIMATE WAS 2.2/32 KT. THEREFORE...THE
 INITIAL INTENSITY WILL REMAIN 35 KT FOR THIS ADVISORY.
 
 THE INITIAL MOTION OF MALIA IS TOWARD THE NORTH-NORTHEAST OR 025
 DEGREES AT 10 KT. THE PRIMARY STEERING MECHANISMS FOR THIS
 SYSTEM ARE A DEEP LAYER TROUGH FAR TO THE WEST NEAR LONGITUDE
 173E...AND A DEEP LAYER RIDGE LOCATED FAR TO THE EAST AND NORTHEAST.
 THE SYSTEM IS EXPECTED TO CONTINUE ON THIS TRACK THROUGH THIS
 MORNING WITH A GRADUAL TURN TOWARD THE NORTH LATER TODAY AND
 TONIGHT. MALIA IS THEN FORECAST TO MOVE TOWARD THE NORTH-NORTHWEST
 AT A FASTER FORWARD SPEED DURING THE 24 TO 36 HOUR TIME PERIOD AS
 THE SYSTEM BECOMES ENTANGLED WITH THE CIRCULATION OF THE DEEP LAYER
 TROUGH. MOST OF THE RELIABLE DYNAMICAL TRACK GUIDANCE REMAINS
 REASONABLY WELL CLUSTERED DURING THE NEXT 36 HOURS...WITH INCREASING
 SPREAD FROM DAYS 2 THROUGH 5. THE LATEST OFFICIAL TRACK IS VERY
 CLOSE TO THE PREVIOUS THROUGH 24 HOURS. AFTER THAT...THE 36 HOUR
 POSITION WAS ACCELERATED AND SHIFTED TO THE LEFT. THIS WAS DONE TO
 BLEND WITH THE 48...72 AND 96 HOUR POSITIONS THAT WERE COORDINATED
 WITH THE OCEAN PREDICTION CENTER /OPC/.
 
 THE LATEST ESTIMATES OF ENVIRONMENTAL VERTICAL WIND SHEAR IN THE
 VICINITY OF FIVE-C WERE WELL IN EXCESS OF 30 KT FROM THE
 WEST-SOUTHWEST ACCORDING TO THE UW-CIMSS AND SHIPS GUIDANCE. THIS
 INCREASING SHEAR COMBINED WITH GRADUAL COOLING OF THE OCEAN WATER
 TEMPERATURES AND HEAT CONTENT UNDER THE FUTURE TRACK OF MALIA ARE
 LIKELY DETRIMENTAL TO THE LONG TERM HEALTH OF THE SYSTEM AS A WARM
 CORE TROPICAL SYSTEM. HOWEVER...THE INCREASING SHEAR HAS LIKELY
 PRODUCED DIFFLUENCE ALOFT ACROSS THE SYSTEM...WHICH HAS CONTINUED TO
 ALLOW THUNDERSTORMS TO DEVELOP IN A LARGE CLUSTER NORTHEAST OF THE
 CENTER. AT THE SAME TIME...THE TIGHTENING OF THE PRESSURE GRADIENT
 BETWEEN MALIA AND THE SUBTROPICAL RIDGE LOCATED MORE THAN 500
 NM TO THE NORTH SHOULD CAUSE SURFACE WINDS TO STEADILY INCREASE...
 ESPECIALLY IN THE NORTH AND NORTHEAST QUADRANTS. AS A RESULT...THE
 SYSTEM WILL LIKELY REMAIN A TROPICAL STORM EVEN IF CONVECTION
 BEGINS TO WEAKEN LATER TODAY OR TONIGHT. MALIA WILL EVENTUALLY BEGIN
 TO UNDERGO AN EXTRATROPICAL TRANSITION...WITH THE CURRENT FORECAST
 NOW SHOWING THIS WILL HAPPEN BEYOND 36 HOURS. THE LATEST OPC INPUT
 INDICATES THIS EXTRATROPICAL TRANSITION WILL OCCUR BETWEEN 36 AND 48
 HOURS. THE 48...72 AND 96 HOUR INTENSITY...AS WELL AS THE 48 AND 72
 HOUR 34 KT WIND RADII FORECASTS WERE ALSO COORDINATED WITH OPC.
  
 A TROPICAL STORM WARNING REMAINS POSTED FOR PORTIONS OF THE
 PAPAHANAUMOKUAKEA MARINE NATIONAL MONUMENT FROM FRENCH FRIGATE
 SHOALS TO MARO REEF TO LISIANSKI ISLAND. TROPICAL STORM CONDITIONS
 WILL CONTINUE OVER MANY OF THESE VULNERABLE LOW LYING ISLANDS AND
 ATOLLS INTO TONIGHT.
  
  
 FORECAST POSITIONS AND MAX WINDS
  
 INIT  21/1500Z 25.1N 171.0W   35 KT  40 MPH
  12H  22/0000Z 26.6N 171.4W   40 KT  45 MPH
  24H  22/1200Z 29.0N 172.2W   40 KT  45 MPH
  36H  23/0000Z 33.0N 174.5W   45 KT  50 MPH
  48H  23/1200Z 38.4N 176.5E   45 KT  50 MPH...POST-TROP/EXTRATROP
  72H  24/1200Z 43.9N 173.3E   40 KT  45 MPH...POST-TROP/EXTRATROP
  96H  25/1200Z 50.4N 169.9E   35 KT  40 MPH...POST-TROP/EXTRATROP
 120H  26/1200Z...DISSIPATED
  
 $$
 FORECASTER HOUSTON